A solid-state image pickup device includes a light receiving section where M×N pixel units P1,1 to PM,N each including a photodiode and a charge accumulating section are two-dimensionally arrayed in M rows and N columns, a row selecting section that causes each pixel unit Pm,n in a light receiving section to accumulate charge generated in its photodiode during a given period in its charge accumulating section, and to output data corresponding to an amount of the charge accumulated in each pixel unit Pm,n in every row, and a readout section for which the data output from each pixel unit Pm,n in the light receiving section is input and from which data corresponding to an amount of charge generated in the photodiode of each pixel unit Pm,n is output. Also, in some cases, the solid-state image pickup device further includes an AD conversion section that analog/digital-converts the data output from the readout section to output a digital value.
Such a solid-state image pickup device is capable of detecting an intensity of light reaching each pixel unit Pm,n in its light receiving section, to perform image pickup. Further, in recent years, not only image pickup, but an attempt has been made to perform optical communication by using such a solid-state image pickup device. For example, in the invention disclosed in Patent Literature 1, it is detected whether or not a temporal intensity change of each of all pixel units in its light receiving section is a predetermined pattern on the basis of image data obtained by image pickup with the solid-state image pickup device, and it is specified that pixel units whose temporal intensity changes are judged as the predetermined pattern have received an optical signal. Then, data from the specified pixel units are considered as optical signal data, thereby performing optical communication.